In the following reaction: 4 Al + 3 O2 –> 2 Al2O3 How many moles of aluminum would be needed to completely react with 90 grams of O2?

molar ratio= 4:3

                   since al moles needed so we will leave al in moles and convert o into grams

             4: since 1 mole of oxygen is 16g so 3 moles is 48

4:48

put given data

x:90

90*4/48

7.5 moles          

Explanation:

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.